SOLAR SYSTEM

Detailed explanation-1: -The dust and gases in a nebula are very spread out, but gravity can slowly begin to pull together clumps of dust and gas. As these clumps get bigger and bigger, their gravity gets stronger and stronger. Eventually, the clump of dust and gas gets so big that it collapses from its own gravity.

Detailed explanation-2: -a protostar is what is formed when a nebula’s gas and dust come closer together. 3. after the protostar gets hot enough nuclear fusion reactions fuse together helium and hydrogen.

Detailed explanation-3: -So, in the developing stage when it is called a protostar there is not sufficient heat energy for the fusion reaction to occur. Thus, a protostar will not engage in the process of nuclear fusion. When it becomes hot enough then fusion starts and it becomes a main-sequence star.

Detailed explanation-4: -Once the temperature reaches 15, 000, 000 degrees Celsius, nuclear fusion takes place in the center, or core, of the cloud. The tremendous heat given off by the nuclear fusion process causes the gas to glow creating a protostar.